Freezer Pickles

Freezer pickles are a quick and easy answer for preserving cucumbers for long-term storage without the cooking and heat processing involved in canned pickles. Because Clostridium botulinum will not grow at freezing temperatures (0°F), and because the product is not in a vacuum seal as in a jar, there is no risk of botulism that there is with canned goods. As a result, there is room to experiment with freezer pickle recipes; you can add spices and herbs, onions, peppers, garlic, etc.

Fresh cucumbers are 90 percent water. Normally, freezing a vegetable with such a high water content would have quality issues because the water forms large ice crystals piercing its tender cell walls. When the food thaws, water is released from the cells, and they collapse, producing a mushy product. Thus, plain cucumbers are not frozen for use in salads.

However, when prepared as a pickle, salt draws out some of the water, and a concentrated sugar syrup firms the pickle; slicing the cucumbers thinly so that cucumbers can absorb the sugar syrup and freezing them quickly results in a high-quality product. 

The most common pickle for freezing is the bread and butter pickle. In this case, they resemble the thinly sliced sweet pickle made in south-central Pennsylvania. Tradition says these pickles were placed on butter bread and made into a sandwich. Many canning recipes for bread and butter pickles are sliced as thick as ½ inch, but that will not work for freezer pickles. 

Making Freezer Pickles

Good quality freezer pickles can be made following these steps.

1. Wash pickles and remove any blemishes. Pickling cucumbers are preferred because they have thinner skin and produce a tenderer product. Cucumbers do not need to be peeled unless the recipe specifies this step. Avoid the use of commercially waxed cucumbers; the wax coating interferes with the absorption of the brine.
2. Slice freezer pickles very thin—almost thin enough to see through. The slices should be 1/16^th to 1/8^th inch thick; this provides more surface area for the salt to remove water and the sweet vinegary syrup to be absorbed. Remember to discard the blossom and the stem ends.
3. Salt thin slices to draw excess water out of the cucumber—excess water can dilute the brine. Less salt is used in freezer pickles than for most canned pickles. For the following directions, a good proportion is 2 tablespoons salt to 8 cups of cucumbers. If you are using other flavorful vegetables such as onion or green, or red pepper, include them in the salting process. Canning or pickling salt should be used to prevent any discoloration from additives found in table or sea salt.
4. Weight down the salted vegetables and cover. Do not add water. Standing time varies from 2 hours to overnight. If standing time is more than 2 hours, place them in the refrigerator. Drain the salted cucumbers, discarding liquid. If you have used less than two teaspoons of salt per 8 cups of cucumbers, rinsing the cucumbers is optional. If you have used more salt, rinsing the cucumbers removes some of the saltiness. Drain well. Meanwhile, prepare the syrup in step 6.
5. You will find a number of syrup recipes for freezer pickles. The best syrups will have a high concentration of sugar to vinegar. The addition of sugar inhibits enzyme changes and yields a firmer, more flavorful product to a vegetable that would not normally freeze successfully. 
6. Prepare a highly concentrated syrup, such as 2 cups sugar to 1 cup vinegar. (This is the amount of syrup for 8 cups of cucumbers.) White or cider vinegar of 5% acidity can be used, although white vinegar maintains color better. Combine, but do not cook the sugar, vinegar, and spices. One teaspoon of celery seed and/or one teaspoon of mustard seed works well with this amount of syrup, but you can choose whatever spices you like. Note: It will take a long time for the sugar to dissolve in the vinegar. Stir until it is very smooth and no sugar crystals remain. (If you are using a recipe that cooks the syrup, cool the syrup before mixing it with the drained cucumbers. In a few recipes, cook the sugar and vinegar to concentrate the syrup and pour it over the drained cucumbers.)
7. Pour the syrup over the drained cucumbers in a bowl and refrigerate for 24 hours. The syrup will continue to draw liquid from the cucumbers
8. Place into freezer containers, allowing ½ inch headspace for the syrup to expand. Place waterproof freezer paper or plastic wrap on top to press the cucumbers under the syrup: cover and freeze. Allow space between the containers in the freezer to allow them to freeze quickly.
9. About 8 cups of thinly sliced cucumbers made with the above syrup will yield about 4 pints of freezer pickles.

The University of Wisconsin Extension publication, Wisconsin Safe Food Preservation Series: Homemade Pickles & Relishes, by Barbara Ingham (2008) has additional recipes for freezer pickles.

Freezer slaw is a version of freezer pickles. The most successful freezer slaws use a syrup made with two parts sugar to one part vinegar. Like pickles, the cabbage is salted briefly before the syrup is added.

Serving Freezer Pickles

Thaw freezer pickles in the refrigerator. Once thawed, they must be kept refrigerated and used within two weeks. When the food thaws and is over 40°F, there is the potential for bacteria to grow, causing foodborne illness. Thus, thawed pickles should not be at room temperature for over two hours. 

References:

Ingham, B. (2008). Wisconsin Safe Food Preservation Series: Homemade Pickles & Relishes.